Hydrothermal Transformation of Eggshell Calcium Carbonate into Apatite Micro-Nanoparticles: Cytocompatibility and Osteoinductive Properties Torres Mansilla, Adriana Fernández Penas, Raquel Gómez Morales, Jaime Calcite Apatite Organic matrix Hydrothermal conversion Cytocompatibility Osteogenic differentiation This research was funded by Spanish Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovación y Universidades (MCIU), Bioscaffold project, ref. PGC2018-102047-B-I00 (MCIU/AEI/FEDER, UE). The Ministry of Science, Technology, and Innovation of Colombia provided support for A.T-M´s participation. P.Á.-L. acknowledge support from MCIN project PCI2019–111931-2 and the European Regional Development Fund–ERDF)—Next Generation/EU program. J.G.-M. acknowledges PCI2020-112108 funded by MCI/AEI/10.13039/501100011033 (Spain) and the European Union “NextGeneration/PRTR”. PCI2020-112108 is part of the CASEAWA project of the ERA-NET Cofund BlueBio Programme, supported by the European Union (H2020). The authors acknowledge the staff of Scientific Instrumentation Centre (CIC) of the University of Granada for HRSEM and TGA characterizations and Scientific and Technical Services of the University of Oviedo for XRD analyses. Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/nano13162299/s1 The eggshell is a biomineral consisting of CaCO3 in the form of calcite phase and a pervading organic matrix (1-3.5 wt.%). Transforming eggshell calcite particles into calcium phosphate (apatite) micro-nanoparticles opens the door to repurposing the eggshell waste as materials with potential biomedical applications, fulfilling the principles of the circular economy. Previous methods to obtain these particles consisted mainly of two steps, the first one involving the calcination of the eggshell. In this research, direct transformation by a one-pot hydrothermal method ranging from 100-200 C-circle was studied, using suspensions with a stoichiometric P/CaCO3 ratio, K2HPO4 as P reagent, and eggshells particles (phi < 50 mu m) both untreated and treated with NaClO to remove surface organic matter. In the untreated group, the complete conversion was achieved at 160 C-circle, and most particles displayed a hexagonal plate morphology, eventually with a central hole. In the treated group, this replacement occurred at 180 C-circle, yielding granular (spherulitic) apatite nanoparticles. The eggshell particles and apatite micro-nanoparticles were cytocompatible when incubated with MG-63 human osteosarcoma cells and m17.ASC murine mesenchymal stem cells and promoted the osteogenic differentiation of m17.ASC cells. The study results are useful for designing and fabricating biocompatible microstructured materials with osteoinductive properties for applications in bone tissue engineering and dentistry. 2023-10-26T08:06:44Z 2023-10-26T08:06:44Z 2023-08-10 journal article Torres-Mansilla, A.; Álvarez-Lloret, P.; Fernández-Penas, R.; D’Urso, A.; Baldión, P.A.; Oltolina, F.; Follenzi, A.; Gómez-Morales, J. Hydrothermal Transformation of Eggshell Calcium Carbonate into Apatite Micro-Nanoparticles: Cytocompatibility and Osteoinductive Properties. Nanomaterials 2023, 13, 2299. [https://doi.org/10.3390/nano13162299] https://hdl.handle.net/10481/85259 10.3390/nano13162299 eng info:eu-repo/grantAgreement/EC/H2020/PCI2020-112108 http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional MDPI